Create your own customized salad mix by purchasing seeds for your favorite baby salad greens. Loose-leaf lettuces are best suited for baby greens - do not get head-forming types. Tasty varieties include Royal Oak Leaf, Salad Bowl, Red Salad bowl, and Tango.
Spinach is a good choice for your baby greens mix, as are chard and beets (grown, of course, for their greens only). If you like a spicy bite to your salad, try arugula, mustard greens, or a spicy cress in your mix.
If you do not want to create your own seed mixture, look for mesclun mix. Most seed companies offer a mesclun mix, which is a combination of salad green seeds that often contains different tastes and textures.